pros and cons of running a 4BT???

[Broncobowsher]

I may have overlooked it, but I have seen the 4BT running and know wome running it. One thing to remember is that it isn't the smoothest running engine. they do shake and rattle the whole rig.

Another factor is that roughness is the torque. Yes they do have very good torque numbers, but it isn't nice smooth V8 torque. It is a hammering torque. Each time a cylinder fires it is a torque spike. Since ther are only 4 cylinders, and they don't turn very fast, each fire is like a hammer blow. 300 ft-lb of V8 gasoline torque is gentle, 300 ft-lb of 4-cylinder low reving diesel is much more brutal on driveline parts.

 

[johnnybgood74]

very true. i undersatnd what your saying broncobowsher. but i dont quite get what your saying about the torque. isnt 300 ft. lbs of torque, 300 ft. lbs of torque even if it comes on stronger and more harsh in a 4BT? not being a smartass or anything but im just trying to figure out how it can be harder on the drivetrain.

 

[Pa PITT]

Very cool car Johnny.. I had a new 1970 SS KIND OF LIKE THAT but not half as stought...

 

[johnnybgood74]

hey thanks PAPITT, to bad i had to sell it do to hard times. i am pretty sad about that one. that car has run a best of 10.20. not to shabby in the quarter mile and thats at 3500 feet! i built that car from the ground up. it was just a shell when i bought for 300 bucks back in the late 90's. i had that car and my 72 Bronco sitting in my garage side by side. i loved opening that door! oh the good ol days!

 

[Broncobowsher]

very true. i undersatnd what your saying broncobowsher. but i dont quite get what your saying about the torque. isnt 300 ft. lbs of torque, 300 ft. lbs of torque even if it comes on stronger and more harsh in a 4BT? not being a smartass or anything but im just trying to figure out how it can be harder on the drivetrain.

If I could do some math and show charts it would be better. But I will try to describe it anyway.

A sine wave, peaks at 350 and valleys at 250. Average is 300 and it is a fairly smooth curve. Gas engine.
A sine wave, peaks at 450 and valleys at 150. Average is 300 and it is a very steep curve. 4-cylinder diesel.

The gas V8 has 4 fairly gently peaks per revolution. Smaller flywheel is needed to smooth it out.
The diesel I4 has 2 big spikes per revolution. Even a bigger heavier flywheel can't smooth out the big nasty spikes.
Those big spikes are what pounds the driveline, a fraction of a turn at a time.

 

[johnnybgood74]

hey thanks Broncobowsher that makes a lot of sense to me now. im not the type of guy to throw the stock drivetrain behind a diesel or a gas engine with a lot of HP. i will do as much bulletproofing as possible. im a big worrywart and that would be all i would thinking about when i drove it. thats why i built the drivetrain in my chevelle so stout. i had no worries when i stabbed the gas pedal.

 

[HoosierDaddy]

my point is that i am certain that a 9" can handle anything i could throw at it with a 4BT. just my 2 cents.

Understood , but how much $$$ did you have to throw into it to get it there , whereas a D60/10.5" will pretty much handle the 4BT stock.

Also understood that the 9" is in hand (free) and the other axles you may have to acquire. Could be a wash money wise , Dana 60 fronts usually aren't cheap.

 

[johnnybgood74]

i had about 1700.00 into it without the wilwood discs. i see your point too. lol i guess with the discs i had about 2300. for that price i could have easily acquired a dana 60 and a 10.5. damn, now the wheels in my head are spinning once again! choosing the right direction for this project is becoming a huge hassel! (not really, but so many routes to go)

 

[Pa PITT]

Johnny did you see the one forsale in classified section .. It's in Calif an $1200.00 ..Good starting place..

 

[blakerj10]

The 4bt is not the monster you guys are making it out to be. Aside from Pappit does anyone in this thread actually have one in a vehicle? Its about the same power as a chevy 6.5, which I also had, in a factory half ton blazer. The drivetrain in the bread vans is heavier because of the vehicles overall GVWR. The 4bt was a replacement engine for a small block v8.

Broncobowsher is right about the torque delivery however. The biggest concern I see for breaking parts is the 4bt delivers the torque right off idle. The tires are not moving, have good traction, and boom, you can hit the drivetrain with instant torque. Not at some higher rpm level where everything is already moving.

Yes there are disadvantages and advantages. But a stock 4bt in a stock bronco, used as a stock bronco was intended, is not going to pretzal a bronco.

 

[00gyrhed]

And you don't think that maybe just maybe a chevy 6.5 would be overdoing it in a vehicl the size and weight of a CB? Then couple that with the fact that that torque is right there off idle you still make the point, thats when you break parts.

 

[blakerj10]

00gyrhed... Not trying to argue with you. No, I don't think either engine would be overkill for an EB. I don't think a modestly built 351 is either.

Just trying to adequately represent the pros and cons - there are both. If the op is excited about doing a diesel swap, the 4bt is a great option.

 

[00gyrhed]

Not arguing, just trying to make sure this guy enters the darkside with his head up and eyes open. Its easy to fall in love with excessive torque, horspower or low gearing, doublers, you name it.

The vast majority of us do not need it and find after a time that it really only complicated our life.

Ive been playing offroad for 30+ years and what I have found is it is best to just stick to the stock driveline in a Bronco. With a D44 front the bronco driveline is almost bullet proof with any of the engines Ford ever put in the truck as long as tire size remains reasonable. A mildly built 302 or 351 will do everything it needs to do offraod and won't litter the trail with expensive driveline parts. Cheaper engines, fewer repairs mean more money in your pocket and more time to wheel.

Once you start the cycle it never ends. Larger tires, truck becomes a dog so need more engine. Put in hot 351. break driveline parts. upgrade driveline parts means more weight. need more HP go to 4BT, upgrade driveline again.

I recommend to anybody that will listen. EFI on your 302 or a 351 built for torque, 33 inch tires, NP435, PS, disc brakes, possibly lockers. Drive it forever. Play with it all you want. You will not be breaking a parts and you will not be working on it all the time. the little 302 will get decent milage and will out accelerate most of what is on the highway. There is very very little that set up will not do.

 

[Devin]

Not arguing, just trying to make sure this guy enters the darkside with his head up and eyes open. Its easy to fall in love with excessive torque, horspower or low gearing, doublers, you name it.

Dark side? Did he mention putting a 335 series motor in?

;D;D;D

 

[Pa PITT]

''The vast majority of us do not need it and find after a time that it really only complicated our life.''
........
........
.....I haven't agreed with most of what has been said ..But I find if I keep my foot off the floor I don't break as much ...I can control my own destiny.
....But that top statement is so true I find on most of my projects.

 

[bingen]

check out the toyota 13BT

I have just been wheeling with diesels and have found the new models, with direct injection, common rail, turbo, etc to be so different from the old days.
But still my two 4X4's, with gasoline V8 engines (Bronco 302 and wrangler with a rover V8) give snapping power and feel like I break more things with the V8 than with my diesel 4X4 (landcruiser with 2B and fortuner 3.0l turbo with variable vane).
The diesels will go anywhere the V8's go with more finesse. But the V8's are really fun and exciting when they kick up gravel and dirt and jump up those climbs, etc!
For a great diesel engine, check the toyota diesels...like the 13BT...i drove a cruiser with that motor and it kicks ass...

http://www.gscruiserparts.com/engines.html

 

[00gyrhed]

''The vast majority of us do not need it and find after a time that it really only complicated our life.''
........
........
.....I haven't agreed with most of what has been said ..But I find if I keep my foot off the floor I don't break as much ...I can control my own destiny.
....But that top statement is so true I find on most of my projects.

so hard to do when its all just right htere waiting for you to press just a little harder.

 

[HoosierDaddy]

I recommend to anybody that will listen. EFI on your 302 or a 351 built for torque, 33 inch tires, NP435, PS, disc brakes, possibly lockers. Drive it forever. Play with it all you want. You will not be breaking a parts and you will not be working on it all the time. the little 302 will get decent milage and will out accelerate most of what is on the highway. There is very very little that set up will not do.

I have been offroading for only a few years , I ran that set up and am amazed at where it can go.

But a stock 4bt in a stock bronco, used as a stock bronco was intended, is not going to pretzal a bronco.

Now where's the FUN in that ?

 

[HoosierDaddy]

This has been a great thread by the way.

Somewhere way down on my "to do list" is building a 4BT (or other diesel) bronco as a daily driver.
Mileage will be the goal , since I am driving 20 to 45 miles each way every day. (construction worker = my job area varies)

Considering the cost of a new superduty , up to 58k , I can justify going over the top if I were to build one .... and still be money ahead. And if I can get it to break into the 22+ MPG's , it will be better than those trucks are capable of and a whole hell of a lot cooler than a Jetta TDI.